With e.g. `CLOCK_BOOTTIME`, it's plausible that less than 1 second has
passed since the boot reference time.
Only assert that the returned time is nonzero (because all-bits-zero is
highly implausible as an actual clock value, but likely indicates that the
intended value was not copied out correctly).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The goal isn't to do any functional testing, but to have a simple diagnostic
if some Unix platform function isn't available, and to have a record of
success in the outcome file.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
